Boosting the energy density of sulfide-based all-solid-state batteries at low temperatures by charging to high voltages up to 6 V

Sulfide electrolyte-based all-solid-state batteries(ASSBs)are potential next generation energy storage technology due to the high ionic conductivity of sulfide electrolytes and potentially improved energy density and safety.However,the performance of ASSBs at/below subzero temperatures has not been explored systematically.Herein,low temperature(LT)performance of LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)|Li_(9.54)Si_(1.74)P_(1.44)S11.7Cl_(0.3)(LiSPSCl)|Li_(4)Ti_(5)O_(12)(LTO)ASSBs was investigated.By charging the ASSB to 6 V at−40℃,a capacity of 100.7 mAh∙g^(−1)at 20 mA∙g^(−1)was achieved,which is much higher than that charged to 4.3 V(4.6 mAh∙g^(−1))at−40℃.Moreover,atomic resolution microscopy revealed that the NCM811 remained almost intact even after being charged to 6 V.In contrast,NCM811 was entirely destructed when charged to 6 V at room temperature.The sharp difference arises from the large internal charge transfer resistance at LT which requires high voltage to overcome.Nevertheless,such high voltage is not harmful to the active material but beneficial to extracting most energy out of the ASSBs at LT.We also demonstrated that thinner electrolyte is favorable for LT operation of ASSBs due to the reduced ion transfer distance.This work provides new strategies to boost the capacity and energy density of sulfide-based ASSBs at LT for dedicated LT applications.

Tailoring lithium concentration in alloy anodes for long cycling and high areal capacity in sulfide-based all solid-state batteries

Lithium–indium(Li-In)alloys are important anode materials for sulfide-based all-solid-state batteries(ASSBs),but how different Li concentrations in the alloy anodes impact the electrochemical performance of ASSBs remains unexplored.This paper systematically investigates the impact that different Li concentrations in Li-In anodes have on the performance of ASSBs.We show that In with 1 wt%Li(LiIn-1)exhibits the best performance for ASSBs among all the tested Li-In anodes.In essence,LiIn-1 not only provides sufficient Li to compensate for first-cycle capacity loss in the anode but also facilitates the formation of a LiIn alloy phase that has the best charge transfer kinetics among all the Li_(x) In alloy phases.The ASSB with a LiIn-1 anode and a LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2) cathode reached 3400 cycles at an initial capacity of 125 mAh/g.Remarkably,ASSBs with a high cathode active material(CAM)loading of 36 mg/cm 2 delivered a high areal capacity of 4.05 mAh/cm^(2) at high current density(4.8 mA/cm^(2)),with a capacity retention of 92% after 740 cycles.At an ultra-high CAM loading of 55.3 mg/cm^(2),the ASSB achieved a stable areal capacity of 8.4 mAh/cm^(2) at current density of 1.7 mA/cm 2.These results bring us one step closer to the practical application of ASSBs.